Low-lead brass alloy for use in member for water works

ABSTRACT

An object of the present invention is to provide a brass alloy, in which the content of Bi is reduced to secure a good recyclability while maintaining the dezincification corrosion resistance required for a member for water works, and which is capable of exhibiting an erosion-corrosion resistance and excellent mechanical properties to be used as a member for water works. This brass alloy contains: 24% by mass or more and 34% by mass or less of Zn; 0.5% by mass or more and 1.7% by mass or less of Sn; 0.4% by mass or more and 1.8% by mass or less of Al; 0.005% by mass or more and 0.2% by mass or less of P; and 0.01% by mass or more and 0.25% by mass or less of Pb; with the balance being copper and an unavoidable impurity(ies).

TECHNICAL FIELD

The present invention relates to a material made of a brass alloy andhaving an erosion-corrosion resistance, designed for use in a member forwater works.

BACKGROUND ART

JIS H5120, CAC 203, a brass casting which has been conventionally usedfor members related to water works, such as tap faucet parts, containsfrom 0.5 to 3.0% by mass of lead, and it has become difficult to complywith the lead regulations for copper alloys for use in members for waterworks, implemented around the world in recent years. Efforts havetherefore been made to produce a copper alloy with a reduced leadcontent, in order to reduce the harmful effect of lead.

However, simply reducing the Pb content results in a decrease in thecastability, machinability and/or pressure resistance of the copperalloy, which could potentially cause water leak when used as a valve,for example. In order to compensate for the changes in the properties ofthe alloy due to reduced content of lead, incorporation of Bi has beenproposed to improve machinability, dezincification corrosion resistanceand/or pressure resistance.

For example, the below-identified Patent Document 1 discloses a brassalloy having a reduced risk of dezincification corrosion and improvedmechanical properties and castability, while having a reduced leadcontent, which brass alloy containing, along with Zn, from 0.4 to 3.2%by mass of Al, from 0.1 to 4.5% by mass of Bi, and from 0.001 to 0.3% bymass of P.

Further, the below-identified Patent Document 2 discloses a brass alloy(for example, No. 6 or No. 20) capable of preventing water qualitydeterioration and having an excellent machinability and abradability atthe time of plating pretreatment, which brass alloy containing from 0.3to 1.0% of Sn, from 0.5 to 1.0% of Ni, from 0.4 to 8% of Al, from 0.01to 0.03% of P, from 1.0 to 2.0% of Bi, and a trace amount of Sb. PatentDocument 2 also discloses a brass alloy further containing from 5 to 10ppm by weight of B, in addition to containing the above mentionedelements within the above ranges.

However, a copper alloy which contains a large amount of Bi for thepurpose of securing the machinability must be separated from othercopper alloys containing no Bi, when subjected to recycling. This isbecause, if a copper alloy containing Pb is contaminated with Bi, forexample, it causes embrittlement of the resulting alloy. Since the alloyaccording to the Patent Document 1 contains Bi, it has the abovementioned problem, and the same problem applies to the alloy accordingto Patent Document 2, specifically, the alloy No. 6 disclosed as anExample therein.

In contrast, a brass alloy is also known which contains no Bi, and whichis useful as a member for water works in terms of recyclability. Forexample, since the alloy No. 20 disclosed as a Comparative Example inPatent Document 2 does not contain Bi, there is no need to carry out thesorting of alloys based on whether or not Bi is contained, at the timeof recycling.

The below-identified Patent Document 3 discloses a copper alloy (forexample, No. 803) for use in wires, which does not contain Bi or Pb, andcontains from 62 to 91 mass % of Cu, from 0.01 to 4 mass % of Sn, from0.0008 to 0.045 mass % of Zr, and from 0.01 to 0.25 mass % of P, withthe balance being Zn. This copper alloy is required to have acomposition in which the contents of Cu, Sn, and P, each in percent bymass, satisfy the relation: 62≦Cu−0.5×Sn−3×P≦90, in addition tocontaining the above mentioned elements within the above contents.Further, the copper alloy is also required to have a phase structure inwhich the total content of α-phase, γ-phase, and β-phase accounts for 95to 100% in terms of area ratio, and to have an average crystal grainsize at the time of melt-solidification of 0.2 mm or less. However, whenthis alloy for use in wires is used as a member for water works, thealloy fails to exhibit sufficient machinability, despite having asufficient recyclability due to containing no Bi.

In cases where a brass alloy is used as a member for water works, thereare other important issues to be addressed, in addition to therecyclability. When used as a member for water works, such as a valve,any brass alloy is susceptible to corrosion induced by the rapid flow ofwater, referred to as an erosion-corrosion. When a brass alloy is incontact with still water, an oxide film is gradually formed on thesurface of the metallic material to prevent corrosion. However, in anenvironment where the alloy is exposed to flowing water, the influenceof the shear force or turbulent flow caused by the flowing water, inaddition to ordinary corrosion, destroys the oxide film, therebyaccelerating the corrosion. The alloy No. 20 disclosed as a ComparativeExample in Patent Document 2 has an insufficient erosion-corrosionresistance. Examples of the brass alloy having an erosion-corrosionresistance, as described above, include alloys disclosed in thebelow-identified Patent Documents 4 to 6.

Patent Document 4 discloses a copper alloy containing from 10 to lessthan 25 wt % of Zn, from 0.005 to 0.070 wt % of P, from 0.05 to 1.0 wt %of Sn, and from 0.05 to 1.0 wt % of Al; and any one or two of from 0.005to 1.0 wt % of Fe and from 0.005 to 0.3 wt % of Pb in a total amount offrom 0.005 to 1.3 wt %; with the balance being copper and an unavoidableimpurity(ies); wherein the alloy has an excellent erosion-corrosionresistance.

Patent Document 5 discloses a copper alloy containing from 25 to 40 wt %of Zn, from 0.005 to 0.070 wt % of P, from 0.05 to 1.0 wt % of Sn, andfrom 0.05 to 1.0 wt % of Al, as essential elements; and any one or twoof from 0.005 to 1.0 wt % of Fe and from 0.005 to 0.3 wt % of Pb in atotal amount of from 0.005 to 1.3 wt %; with the balance being copperand an unavoidable impurity(ies); wherein the alloy has a crystal grainsize of 0.015 mm or less and an excellent dezincification corrosionresistance.

Further, Patent Document 6 discloses a copper alloy containing from 25to 40 wt % of Zn, from 0.005 to 0.070 wt % of P, from 0.05 to 1.0 wt %of Sn, from 0.05 to 1.0 wt % of Al, and from 0.005 to 1.0 wt % of Si, asessential elements; and any one or two of from 0.005 to 1.0 wt % of Feand from 0.005 to 0.3 wt % of Pb in a total amount of from 0.005 to 1.3wt %; with the balance being copper and an unavoidable impurity(ies);wherein the alloy is characterized by being subjected to cold rolling atreduction of sectional area of 3 to 20%, after final annealing, andhaving an excellent dezincification corrosion resistance.

In addition, the below-identified Patent Document 7 discloses copperalloys containing Zr and/or Te as a trace element(s). Disclosed thereinis a copper alloy containing from 8 to 40% of Zn, from 0.0005 to 0.04%of Zr, and from 0.01 to 0.25% of P; and one or more than one of from 2to 5% of Si, from 0.05 to 6% by mass of Sn, and from 0.05 to 3.5% bymass of Al; with the balance being Cu and an unavoidable impurity(ies).Also disclosed therein, as Example 105, is a copper alloy which does notcontain Si or Bi, and contains 27% of Zn, 0.8% of Sn, 0.8% of Al, 0.05%of P, 0.18% of Pb, 0.005% of Zr, and 0.12% of Te.

Moreover, the below-identified Patent Document 8 describes a findingthat it is possible to obtain an alloy satisfying required physicalproperties by integrating the influence of each of the elements in termsof zinc equivalent (Zneq), and allowing the zinc equivalent Zneq tosatisfy a certain Inequality. Note, however, that the alloy in the abovementioned description contains Bi. Specifically, the alloy contains:from 0.4 to 2.5% by mass of Al; 0.001 to 0.3% by mass of P; 0.1 to 4.5%by mass of Bi; from 0 to 5.5% by mass of Ni; from 0 to 0.5% by mass eachof Mn, Fe, Pb, Sn, Si, Mg, and Cd; and Zn; with the balance being Cu andan unavoidable impurity(ies). Further, in the above mentioned alloy, itis required that the Zneq and the content of Al satisfy the followingInequalities (1) and (2):

Zneq+1.7×Al≧35.0  (1)

Zneq−0.45×Al≦37.0  (2).

PRIOR ART DOCUMENTS Patent Documents

Patent Document 1: WO 2013/145964 A1

Patent Document 2: JP 2000-239765 A

Patent Document 3: JP 4094044 B

Patent Document 4: JP 60-138034 A

Patent Document 5: JP 61-199043 A

Patent Document 6: JP 62-30862 A

Patent Document 7: WO 2007/091690 A1

Patent Document 8: JP 5522582 B

SUMMARY OF THE INVENTION Problems to be Solved by the Invention

However, since the alloy according to Patent Document 4 has a low Zncontent, its tensile strength is insufficient, thereby causing problemsin mechanical properties. In addition, although it is alleged thereinthat the alloy has an erosion-corrosion resistance, its Sri content ispractically insufficient to provide a sufficient erosion-corrosionresistance.

Further, since the alloys disclosed in Patent Documents 5 and 6 containa large amount of Zn, they have problems that the elongation tends to beinsufficient, and that the dezincification corrosion is likely to occur.The alloys also have an insufficient erosion-corrosion resistance.

In addition, since the alloys disclosed in Patent Document 7 contain Zrand/or Te as an essential element(s), problems may occur when used as amixture with other copper alloys. In particular, since Te is toxic, theuse of this alloy as a member for water works is not desirable in thefirst place.

Still further, since the alloy disclosed in Patent Document 8 containsBi, it cannot be recycled along with other common copper alloyscontaining Pb. This alloy also has a problem of insufficienterosion-corrosion resistance.

Accordingly, an object of the present invention is to provide a brassalloy, in which the contents of toxic elements are reduced whilemaintaining the dezincification corrosion resistance required for amember for water works; which is capable of exhibiting anerosion-corrosion resistance while having a reduced Bi content to securea good recyclability; and which has excellent mechanical properties tobe used as a member for water works.

Means for Solving the Problems

The present invention has solved the above mentioned problems byproviding a low-lead brass alloy for use in a member for water works,the brass alloy comprising: 24% by mass or more and 34% by mass or lessof Zn; 0.5% by mass or more and 1.7% by mass or less of Sn; 0.4% by massor more and 1.8% by mass or less of Al; 0.005% by mass or more and 0.2%by mass or less of P; and 0.01% by mass or more and 0.25% by mass orless of Pb; with the balance being copper and an unavoidableimpurity(ies);

wherein, in cases where the brass alloy has a content of Sn of less than1.0% by mass, the contents of Al and Sn in % by mass satisfy thefollowing Inequality (3):

Al+2×Sn≧2.8  (3).

Although the content of Pb is lower the better, Pb contributes toimproving the machinability of the alloy, even in a small amount withinthe range in which its adverse effects on health are limited. Further,Pb and Al—P compounds work in combination to serve as chip breakers, andsignificantly contribute to improving the machinability. This allows thealloy to have a sufficient machinability, making it suitable for amember for water works. Further, the incorporation of a specified amountof Sn allows the alloy to exhibit mechanical properties required for abrass alloy having a high content of Zn, such as tensile strength,elongation, and 0.2% proof stress, while exhibiting durability againsterosion-corrosion.

In cases where the Sn content is less than 1.0% by mass, it is necessarythat the alloy meet a further requirement that the relationship betweenthe Sn content and the Al content satisfy the above mentioned Inequality(3) in order to secure the erosion-corrosion resistance. While both Aland Sn are involved in the erosion-corrosion resistance, in cases wherethe Sn content is less than 1.0% by mass, in particular, Sn has twice asmuch influence on the improvement of the erosion-corrosion resistance asAl does. Therefore, it is required that the above mentioned Inequality(3) be satisfied, in order to obtain necessary physical properties whilesecuring a good balance of the erosion-corrosion resistance and physicalproperties in the alloy. On the other hand, when the Sn content is 1.0%by mass or more, a sufficient erosion-corrosion resistance and the 0.2%proof stress can both be secured, even if the above mentioned Inequality(3) is not satisfied.

As with Pb, Si is also known as an element capable of improving themachinability. However, the brass alloy according to the presentinvention contains Si in an amount less than the amount contained as anunavoidable impurity(ies).

This is because Si tends to produce an oxide which causes problems inrecyclability and mechanical properties, particularly, in elongation. Inaddition, Si may potentially cause a reduction in the erosion-corrosionresistance. When 0.015% by mass or less of B is further incorporatedinto the brass alloy having the above mentioned composition, as avariation of the brass alloy according to the present invention, thedezincification corrosion resistance is markedly improved.

Further, when 1.8% by mass or less of Ni is further incorporated intothe brass alloy having the above mentioned composition, as anothervariation of the brass alloy according to the present invention, thedezincification corrosion resistance is markedly improved.

Effect of the Invention

The present invention allows for producing a member for water works madeof a brass alloy which has a good machinability and erosion-corrosionresistance while having a reduced Bi content to improve therecyclability, and in which safety, durability, and convenience areensured.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating a tensile test evaluationmethod.

FIG. 2 is a schematic diagram illustrating an erosion-corrosion testapparatus.

FIG. 3 shows standards for evaluating machining chips obtained in amachinability test.

FIG. 4 is a graph obtained by plotting the maximum erosion-corrosiondepth against the content of Sn, of alloys of Examples.

FIG. 5 is a graph obtained by plotting the maximum erosion-corrosiondepth against the value T of Equation (4), of the alloys of Examples.

FIG. 6 shows photographs of machining chips obtained in themachinability test.

MODE FOR CARRYING OUT THE INVENTION

The present invention will now be described in detail.

The present invention relates to a brass alloy for use in a member forwater works which contains at least Zn, Sn, Al, P, and Pb.

It is necessary that the above mentioned brass alloy contain 24% by massor more of Zn. Preferably, the Zn content is 27% by mass or more. A Zncontent of less than 24% by mass results in an insufficient tensilestrength, thereby causing problems in mechanical properties. When the Zncontent is 27% by mass or more, the resulting brass alloy has asufficient 0.2% proof stress, and thus has an excellent strength. At thesame time, it is necessary that the Zn content be 34% by mass or less.Preferably, the Zn content is 32% by mass or less. Too high a Zn contenttends to result in an insufficient elongation. Further, a Zn contentexceeding 34% by mass leads to an excessive increase in thedezincification corrosion.

It is necessary that the above mentioned brass alloy have a Sn contentof 0.5% by mass or more. If the Sn content is less than 0.5% by mass,the resulting alloy has an insufficient resistance to erosion-corrosion.A Sn content of 1.0% by mass or more is preferred, because the resultingalloy has a sufficient erosion-corrosion resistance and a sufficient0.2% proof stress. At the same time, it is necessary that the Sn contentbe 1.7% by mass or less. Preferably, the content is 1.3% by mass orless. This is because too high a Sn content tends to results in too lowan elongation. Further, in cases where the Sn content is less than 1.0%by mass, it is necessary that the relationship between the Sn contentand the Al content satisfy Inequality (3) to be described later, inorder to secure the erosion-corrosion resistance.

It is necessary that the above mentioned brass alloy have an Al contentof 0.4% by mass or more. Preferably, the Al content is 0.6% by mass ormore. An Al content of less than 0.4% by mass results in an insufficienttensile strength and/or 0.2% proof stress, thereby causing problems inmechanical properties. Further, compounds formed between Al and P to bedescribed later significantly contribute to the improvement in themachinability. However, if the Al content is deficient, the effectprovided by the compounds will also be insufficient. At the same time,it is necessary that the Al content be 1.8% by mass or less. Preferably,the content is 1.3% by mass or less. An Al content exceeding 1.8% bymass may results in too low an elongation.

In cases where the Sn content is less than 1.0% by mass, it is necessarythat the relationship between the Sn content and the Al content in thealloy satisfy the following Inequality (3). The maximum depth of thecavities caused by erosion-corrosion tends to decrease when either ofthe Al content and the Sn content is increased. However, in cases wherethe Sn content is within the range of less than 1.0% by mass, inparticular, an increase in the Sn content has twice as large an effectas an increase in the Al content does in improving the erosion-corrosionresistance.

Al+2×Sn≧2.8  (3)

It is necessary that the above mentioned brass alloy have a P content of0.005% by mass or more. Preferably, the P content is 0.01% by mass ormore. Too low a P content reduces the effect of improving themachinability provided by the Al—P compounds formed between P and Al,and the resulting alloy tends to produce continuous machining chips.Further, since P exhibits a deoxidizing effect, too low a P contentleads to a decrease in the deoxidizing effect during casting, therebyresulting in an increased occurrence of gas defects, as well as adecreased fluidity due to oxidation of molten metal. At the same time,it is necessary that the P content be 0.2% by mass or less. Preferably,the P content is 0.15% by mass or less. Too high a P content leads to anincreased formation of hard Al—P compounds and the like, therebyresulting in a decrease in the elongation. Further, P reacts with waterin the mold to increase the occurrence of gas defects and shrinkagecavity defects.

It is necessary that the above mentioned brass alloy have a Pb contentof 0.01% by mass or more. Preferably, the Pb content is 0.03% by mass ormore. The presence of Pb contributes to an improved machinability of thealloy, along with the Al—P compounds, but if the Pb content is less than0.01% by mass, there is a potential risk that the machinability may beinsufficient. Since the above mentioned brass alloy contains Sn, whichleads to the formation of hard γ-phase, in particular, the effect ofimproving the machinability provided by Pb is indispensable. On theother hand, if the Pb content exceeds 0.25% by mass, it becomesdifficult to comply with the leaching standards for alloys for use inmembers for water works, depending on the district in which it is used.Accordingly, it is necessary that the Pb content be 0.25% by mass orless, at maximum.

The above mentioned brass alloy may contain as the balance, in additionto Cu, an element(s) other than those described above as an unavoidableimpurity(ies), which are inevitably included in the alloy due to theproblems associated with raw materials or the production process.However, it is necessary that these elements be contained within theranges in which the effect of the present invention is not impaired.This is because, when too large amounts of unexpected elements areincorporated into the alloy, even if the above mentioned elements arecontained within the above mentioned ranges, there is a potential riskthat the physical properties of the alloy may be deteriorated. The totalcontent of the unavoidable impurities is preferably less than 1.0% bymass, and more preferably, less than 0.5% by mass.

Among the above mentioned unavoidable impurities, the content of Si ispreferably less than 0.2% by mass, more preferably, less than 0.1% bymass, and still more preferably, less than the detection limit. Too higha Si content accelerates the entrainment of oxides, decrease inelongation, and occurrence of shrinkage cavities, resulting in a failureto produce a decent casting.

Among the above mentioned unavoidable impurities, it is necessary thatthe content of Bi be less than 0.3% by mass. The Bi content ispreferably less than 0.1% by mass, and still more preferably, less thanthe detection limit. This is because, if the alloy contains anunignorable amount of Bi, the products made therefrom must be recycledseparately, thereby complicating the recycling process. If the Bicontent exceeds 0.3% by mass, the coexistence of Bi in combination withPb contained in the brass alloy according to the present invention maycause an insufficient elongation, and there is a potential risk thatproblems in mechanical properties could occur.

The content of each of the elements which are considered as theunavoidable impurities, is preferably less than OA % by mass, morepreferably, less than 0.2% by mass, and still more preferably, less thanthe detection limit. Examples of such impurities include Fe, Mn, Cr, Zr,Mg, Ti, Te, Se, Cd and the like. Among these, in particular, thecontents of Se, Cd, and Te, which are known to be toxic, are eachpreferably less than 0.1% by mass, and more preferably, less than thedetection limit. Further, the content of Zr, which increases theoccurrence of shrinkage cavity defects, is preferably less than 0.1% bymass, and still more preferably, less than the detection limit.

On the other hand, when the above mentioned brass alloy contains 0.0005%by mass or more of B as an intentionally included element, apart fromthe above mentioned unavoidable impurities, the dezincificationcorrosion resistance is significantly improved. This is because thepresence of B causes the crystal grains to be refined and to be formedinto shapes less susceptible to dezincification corrosion. The contentof B is preferably 0.0007% by mass or more, because the dezincificationcorrosion resistance is further improved. On the other hand, if the Bcontent exceeds 0.015% by mass, a large amount of hard compounds isformed within the texture of the alloy, potentially causing adverseeffects on machinability or elongation.

Further, the above mentioned brass alloy may contain Ni as anintentionally included element, apart from the unavoidable impurities.When the Ni content is 0.1% by mass or more, the surface area ofα-phase, which has an excellent corrosion resistance, is increased,thereby improving the dezincification corrosion resistance of the brassalloy. It is possible to adjust the composition such that the alloybenefits from both the effect provided by containing B, and the effectprovided by containing Ni. At the same time, the Ni content ispreferably 1.8% by mass or less, and more preferably, 0.5% by mass orless. The addition of an excessive amount of Ni increases the amount ofa phase having a high Sn content, and the resulting alloy tends to havea reduced elongation and/or machinability. A Ni content of greater than1.8% by mass results in an unignorable decrease in elongation. In orderto certainly prevent a decrease in elongation, the Ni content ispreferably 0.5% by mass or less.

Further, the above mentioned brass alloy may contain both B and Ni asintentionally included elements, within the above described ranges.

Note, however, that the values of the contents of elements as used inthe present invention indicate the contents thereof in the resultingalloy produced by casting or forging, not the contents in the rawmaterials.

The balance of the above mentioned brass alloy is Cu. The brass alloyaccording to the present invention can be obtained by a common methodfor producing a copper alloy, and when a member for water works isproduced using this brass alloy, a common production method (such ascasting, rolling, or forging) can be used. Examples of the productionmethod include a method in which an alloy is melted using an oilfurnace, gas furnace, high-frequency induction melting furnace, or thelike, and then cast using a mold in a variety of shapes.

EXAMPLES

The brass alloy according to the present invention will now be describedwith reference to Examples in which the brass alloys were actuallyproduced. First, test methods carried out for the brass alloys will bedescribed.

<Tensile Test Method>

A sample prepared by casting in a metal mold having a size of 28 mmdiameter×200 mm length was processed into a type 14A test specimendefined in JIS Z2241. The specific shape of the test specimen is asshown in FIG. 1. The test specimen is a proportional test piece in whichthe original sectional area S₀ and the original gauge length L₀ of theparallel portion satisfy the relationship represented by the equation:L₀=5.65×S₀̂ (½). The diameter d₀ of the rod-like portion was 4 mm, theoriginal gauge length L₀ was 20 mm, the length L_(c) of the parallelportion which was cylindrical was 30 mm, and the radius R of theshoulder portions was 15 mm. (L₀=5.65×(2×2×π)̂(½)=20.04)

The test specimen was subjected to a tensile test according to JIS Z2241and the tensile strength (MPa), the 0.2% proof stress (MPa) and theelongation (%) were evaluated as follows. The tensile strength wasdefined as the maximum test force Fm, which was the force the testspecimen withstood during the test until it exhibited discontinuousyielding. The 0.2% proof stress is the value of the stress when theplastic elongation expressed in percentage relative to the originalgauge length L₀ equals to 0.2%. The elongation is the value of thepermanent elongation of the test specimen after the test, obtained bycontinuing the test until it ruptures, expressed in percentage relativeto the original gauge length L_(o).

-   -   The tensile strength was evaluated according to the following        standards: “Good” (G): 300 MPa or more; “Fair” (F): 250 MPa or        more and less than 300 MPa, and “Insufficient” (I): less than        250 MPa.    -   The 0.2% proof stress was evaluated according to the following        standards: “Good” (G): 100 MPa or more, “Fair” (F): 80 MPa or        more and less than 100 MPa, and “Insufficient” (I): less than 80        MPa.    -   The elongation was evaluated according to the following        standards: “Good” (G): 25% or more, “Fair” (F): 20% or more and        less than 25%, and “Insufficient” (I): less than 20%.

<Erosion-Corrosion Test>

A sample prepared by casting in a metal mold having a size of 20 mmdiameter×120 mm length was cut into a cylinder having a diameter of 16mm as shown in FIG. 2, to be used as a test specimen 12. A nozzle 11having a bore diameter of 1.6 mm was disposed at a position 0.4 mmspaced apart from the test specimen 12, and a 1% aqueous solution ofCuCl₂ 13 was allowed to continuously flow from the nozzle 11 toward thesample at a flow rate of 0.4 L/min for 5 hours. Then the amount of theweight lost (abrasion weight loss), which is the difference in weight ofthe sample before and after the test, and the maximum erosion-corrosiondepth in the sample were measured.

-   -   The abrasion weight loss was evaluated according to the        following standards: “Good” (G): less than 250 mg, “Fair” (F):        250 mg or more and less than 350 mg, and “Insufficient” (I): 350        mg or more.    -   The maximum erosion-corrosion depth was evaluated according to        the following standards: “Good” (G): 150 μm or less, “Fair” (F):        150 μm or more and 200 μm or less, and “Insufficient” (1): 200        μm or more.

<Drilling Test>

Each of the alloys was subjected to a drilling test using a drillingmachine. The drilling test was carried out using the samples each formedby machining to a size of 18 mm diameter×20 mm height, and using adrilling machine, under the drilling conditions shown in Table 1. Theevaluation was carried out as follows. The time required to drill a 5 mmhole in each of the samples was measured, and those with the results of20 seconds or less were evaluated as “Good” (G), those with the resultsof more than 20 seconds and 25 seconds or less were evaluated as “Fair”(F), those with the results of more than 25 seconds were evaluated as“Insufficient” (I).

TABLE 1 Items Conditions Cutting tool Material High-speed steel(SDD0600; manufactured by Cutting Diameter: 6 mm Mitsubishi Corporation)diameter Total 102 mm length Flute 70 mm length Point angle 118 degreeLoad 25 kg Rotational speed 960 rpm Drilling depth 5 mm

<Lathe Machining Test>

For each of the alloys to be tested, a sample prepared by casting in ametal mold having a size of 28 mm diameter×200 mm length was subjectedto dry machining on a universal lathe, with a cemented carbides and/orhard metals brazed tool, at a feed of 0.15 mm/rev and a rotational speed550 of rpm, to obtain machining chips. The machining chips werecategorized based on their shapes as shown in FIG. 3. The evaluation wascarried out as follows: those having favorable shapes were evaluated as“Good” (G), and those having unfavorable shapes were evaluated as“Insufficient” (I).

<Dezincification Corrosion Test Method>

A sample prepared by casting in a metal mold having a size of 28 mmdiameter×200 mm length was cut out into a cubic test specimen of 10mm×10 mm×10 mm, and the test was performed according to ISO 6509.Specifically, the surroundings of the test specimen was covered with anepoxy resin having a thickness of 15 mm or more such that only onesurface of the test specimen was exposed from the resin. After 100 mm²of this exposed surface was polished with wet abrasive paper, theexposed surface was finished with No. 1200 abrasive paper, and washedwith ethanol immediately before the test. This sample embedded in theepoxy resin with only one surface exposed was immersed in 250 mL of a12.7 g/L aqueous solution of cupric chloride at 75±5° C. for 24 hours.After the completion of the test, the sample was washed with water,rinsed with ethanol, and the dezincification depth in its cross sectionwas immediately measured using a light microscope. Specifically, anarbitrary line of 10 mm on cross-section of the exposed surface wasdivided into 5 visual fields and the dezincification depths of thepoints having the minimum and the maximum depths in each of the visualfields were measured. The mean value of the total 10 points was taken asthe average dezincification corrosion depth, and the depth of thedeepest point of all these 10 points was taken as the maximumdezincification corrosion depth. The average and maximum dezincificationcorrosion depths were evaluated as follows, and those having evaluationsother than “insufficient” for both the dezincification depths weredefined as “pass”.

-   -   The average dezincification corrosion depth was evaluated        according to the following standards: “Very Good” (V): less than        50 μm, “Good” (G): 50 μm or more and less than 100 μm, “Fair”        (F): 100 μm or more and less than 200 μm, and “Insufficient”        (1): 200 μm or more.    -   The maximum dezincification corrosion depth was evaluated        according to the following standards: “Very Good” (V): less than        100 μm, “Good” (G): 100 μm or more and less than 200 μm, “Fair”        (F): 200 μm or more and less than 400 μm, and “Insufficient”        (I): 400 μm or more.

<Sample Production Method>

Materials composed of each of the elements were mixed, and melted in ahigh frequency induction melting furnace, followed by casting to producesamples each having the composition as shown in each of the Tables. Allthe values of the contents of the elements are expressed in % by mass,and are values measured in the resulting castings after the production.The following tests were carried out for each of the resulting copperalloys. Note that, the content of each of Sb, Si, and Fe was less thanthe detection limit, in each of the alloys of Examples and ComparativeExamples shown in the Tables. Elements which are not shown in theTables, or the blanks therein, indicate that the contents of therespective elements are less than the detection limit.

First, each of the Sn content and the Al content were varied to examinethe test results of the alloy in relation to the Inequality (3). Thecomponents used in the evaluation, and the results of the mechanicalproperties test and erosion-corrosion (EC) test are shown in Table 2.FIG. 4 shows line graphs obtained by plotting the data of the aboveobtained results, categorized in 3 groups based on the concentration ofAl, with the values the maximum erosion-corrosion depth on the verticalaxis against the values of the Sn content on the horizontal axis. InTable 2, Test Examples 1 to 4 are alloys having an Al content of 0.6% bymass, Test Examples 5 to 8 are alloys having an Al content of 1.0% bymass, and Test Examples 9 to 12 are alloys having an Al content of 1.7%by mass. Test Examples are arranged in the order based on the content ofSn, in increasing order from top to bottom, within each of the groupsbased on the Al concentration.

TABLE 2 Mechanical properties EC 0.2% Abrasion Tensile Elonga- proofweight Maximum Experiment Chemical components (% by mass) strength tionstress loss depth No. Zn Al P Pb Sn Cu (MPa) (%) (MPa) (mg) (μm) TestExample 1 28.62 0.61 0.061 0.073 0.72 Bal 303.9 G 30.4 G 105.5 G 266 F257 I Test Example 2 28.60 0.61 0.060 0.081 0.90 Bal 307.1 G 28.9 G107.7 G 255 F 211 I Test Example 3 28.32 0.61 0.058 0.075 1.02 Bal 301.6G 28.3 G 114.6 G 216 G 143 G Test Example 4 28.77 0.61 0.065 0.065 1.23Bal 346.5 G 25.2 G 131.1 G 218 G 104 G Test Example 5 28.52 1.02 0.0610.070 0.71 Bal 340.1 G 28.1 G 124.3 G 261 F 214 I Test Example 6 28.541.01 0.062 0.065 0.91 Bal 350.1 G 28.2 G 129.8 G 216 G 173 F TestExample 7 28.51 1.02 0.062 0.072 1.03 Bal 350.9 G 26.3 G 134.2 G 195 G134 G Test Example 8 28.34 1.02 0.062 0.066 1.21 Bal 381.7 G 24.2 F145.5 G 192 G 108 G Test Example 9 27.81 1.68 0.061 0.068 0.72 Bal 305.2G 25.7 G 130.6 G 216 G 171 F Test Example 27.96 1.70 0.065 0.074 0.90Bal 328.4 G 26.8 G 135.8 G 214 G 163 F 10 Test Example 28.01 1.69 0.0620.065 1.02 Bal 343.2 G 24.5 F 142.3 G 173 G 130 G 11 Test Example 27.971.69 0.061 0.070 1.21 Bal 389.1 G 21.9 F 143.7 G 172 G 112 G 12

The test results revealed that the erosion-corrosion (EC) maximum depthwas markedly reduced in the alloys of Test Examples having a Sn contentwithin the range of 1.0% by mass or more, as compared to the alloys ofthe Test Examples having a Sn content within the range of less than 1.0%by mass, regardless of the Al content. Further, the results alsoindicated that, when the Sn content is the same, the higher the Alcontent is, the more reduced the maximum erosion-corrosion depth is.However, the above mentioned tendency was markedly observed,particularly in cases where the Sn content is within the range of lessthan 1.0% by mass.

Therefore, among the alloys of Test Examples, those having a Sn contentof less than 1.0% by mass were examined. Specifically, the alloys ofTest Examples 1 and 2 having an Al content of 0.6% by mass, TestExamples 5 and 6 having an Al content of 1.0% by mass, and Test Examples9 and 10 having an Al content of 1.7% by mass were selected, which areshown in Table 3. Of these, the alloys of Test Examples 1, 2, and 5 wereevaluated as having an “Insufficient” in the maximum erosion-corrosiondepth. The Sn content in the alloy of Test Example 2 is about 0.2% bymass higher than that of Test Example 1. Further, the Al content in thealloy of Test Example 5 is about 0.4% by mass higher than that of TestExample 1. The values of the maximum erosion-corrosion depth of TestExample 2 and Test Example 5 are almost the same. In other words, thealloy of Test Example 2 with a Sn content 0.2% higher than that of TestExample 1, and the alloy of Test Example 5 with an Al content 0.4%higher than that of Test Example 1, have the same level of reduction inthe maximum erosion-corrosion depth relative to the alloy of TestExample 1. Consequently, it is assumed that, in the improvement in theerosion-corrosion resistance, which is observed as the reduction in themaximum erosion-corrosion depth associated with an increase in the Sn orAl content, an increase in the Sn content has twice as large an effectas an increase in the Al content does, when the Sn content is within therange of less than 1.0% by mass. Thus, the value T represented by thefollowing Equation (4) can be used as an index for the erosion-corrosionresistance.

TABLE 3 EC Abrasion weight Maximum Experiment Chemical components (% bymass) loss depth No. Zn Al P Pb Sn Cu (mg) (μm) Equation (4): T TestExample 1 28.62 0.61 0.061 0.073 0.72 Bal 266 F 257 I 2.05 Test Example2 28.60 0.61 0.060 0.081 0.90 Bal 255 F 211 I 2.41 Test Example 5 28.521.02 0.061 0.070 0.71 Bal 261 F 214 I 2.44 Test Example 6 28.54 1.010.062 0.065 0.91 Bal 216 G 173 F 2.83 Test Example 9 27.81 1.68 0.0610.068 0.72 Bal 216 G 171 F 3.12 Test Example 27.96 1.70 0.065 0.074 0.90Bal 214 G 163 F 3.50 10

T=Al+2×Sn  (4)

FIG. 5 shows a graph obtained by plotting the data shown in Table 2,with the values of the maximum erosion-corrosion depth on the verticalaxis against the values of Equation (4) on the horizontal axis. Theresult revealed that, when the value T of Equation (4) is within therange of less than 2.8, the value of the maximum erosion-corrosion depthtends to decrease in an approximately linear manner, as the value T ofEquation (4) increases. Further, when the value T of Equation (4) iswithin the range of 2.8 or more, the value of the maximumerosion-corrosion depth tends to remain approximately the same. Based onthe above, it was confirmed that in cases where the alloy has a Sncontent of less than 1.0% by mass, it is possible to secure a sufficienterosion-corrosion resistance by allowing the Sn content and the Alcontent to satisfy the above described Inequality (3).

In the above mentioned Test Examples, the alloys of Test Examples 3, 4,and 6 to 12 correspond to the alloys of Examples according to thepresent invention. Of these, the alloys of Test Examples 6, 9, and 10have a Sn content of less than 1.0% by mass, and meet the requirement tosatisfy the above mentioned Inequality T≧2.8, and thus correspond to thealloys of Examples according to the present invention. On the otherhand, the alloys of Test Examples 3, 4, 7, 8, 11, and 12 meet therequirement to have a Sn content of 1.0% by mass or more, and thuscorrespond to the alloys of Examples according to the present invention.

Next, the changes in the mechanical properties and the erosion-corrosionresistance when the contents of Zn, Al, P, Sn and Pb were varied wereevaluated by the tensile test and the erosion-corrosion test. Thecontents of the respective components and the test results of therespective alloys are shown in Table 4.

TABLE 4 Mechanical properties EC Tensile Abrasion Chemical componentsstrength Elongation 0.2% proof weight Maximum Zn Al P Pb Sn Bi Cu (MPa)(%) stress (MPa) loss (mg) depth (μm) Total Zn Comparative Example 121.00 1.00 0.059 0.073 1.27 0.000 Bal. 220.5 I 23.4 F 84.0 F 212 G 141 GI Example 1 24.54 1.02 0.057 0.063 1.19 0.000 Bal. 257.0 F 30.0 G 89.5 F201 G 132 G F Example 2 27.50 1.03 0.058 0.053 1.21 0.000 Bal. 385.0 G25.1 G 125.0 G 198 G 120 G G Example 3 30.17 1.06 0.057 0.063 1.21 0.000Bal. 392.0 G 26.9 G 147.5 G 188 G 128 G G Comparative Example 2 34.871.00 0.058 0.057 1.18 0.000 Bal. 401.0 G 19.1 I 175.5 G 210 G 138 G I AlComparative Example 3 30.69 0.00 0.059 0.065 1.09 0.000 Bal. 221.0 I35.2 G 77.2 I 254 F 121 G I Example 4 30.83 0.39 0.060 0.074 1.13 0.000Bal. 290.5 F 33.4 G 94.5 F 222 G 136 G F Example 5 30.25 0.65 0.0580.064 1.17 0.000 Bal. 366.4 G 29.9 G 125.5 G 202 G 138 G G Example 330.17 1.06 0.057 0.063 1.21 0.000 Bal. 392.0 G 26.9 G 147.5 G 188 G 128G G Example 6 29.75 1.66 0.056 0.626 1.18 0.000 Bal. 399.0 G 21.2 F158.5 G 182 G 141 G F Comparative Example 4 29.66 2.12 0.059 0.054 1.140.000 Bal. 410.0 G 16.1 I 179.0 G 172 G 190 F I P Example 7 29.93 1.000.036 0.054 1.14 0.000 Bal. 345.5 G 29.3 G 125.5 G 228 G 123 G G Example3 30.17 1.06 0.057 0.063 1.21 0.000 Bal. 392.0 G 26.9 G 147.5 G 188 G118 G G Example 8 29.79 1.02 0.121 0.070 1.12 0.000 Bal. 381.0 G 27.0 G151.5 G 252 F 168 F F Comparative Example 5 29.50 1.02 0.235 0.060 1.160.000 Bal. 361.0 G 19.6 I 151.5 G 287 F 188 F I Sn Comparative Example 629.28 1.01 0.059 0.060 0.11 0.000 Bal. 294.5 F 51.4 G 96.0 F 389 I 497 II Comparative Example 7 29.69 1.03 0.060 0.064 0.31 0.000 Bal. 302.0 G45.0 G 101.5 G 278 F 288 I I Example 9 30.10 1.00 0.055 0.066 0.91 0.000Bal. 388.0 G 34.5 G 138.2 G 206 G 162 F F Example 3 30.17 1.06 0.0570.063 1.21 0.000 Bal. 392.0 G 26.9 G 147.5 G 178 G 128 G G Example 1029.70 0.99 0.061 0.064 1.54 0.000 Bal. 382.5 G 22.4 F 144.8 G 188 G 108G F Comparative Example 8 30.05 1.01 0.062 0.062 1.75 0.000 Bal. 349.5 G18.3 I 139.5 G 177 G 114 G I Comparative Example 9 29.64 1.00 0.0610.063 2.19 0.000 Bal. 390.5 G 9.4 I 182.5 G 174 G 116 G I Pb Example 1129.40 1.04 0.056 0.025 1.05 0.000 Bal. 323.0 G 29.4 G 110.5 G 188 G 122G G Example 3 30.17 1.06 0.057 0.063 1.21 0.000 Bal. 392.0 G 26.9 G147.5 G 178 G 118 G G Example 12 30.11 1.02 0.055 0.233 1.19 0.000 Bal.358.0 G 23.3 F 148.2 G 174 G 120 G F

Firstly, alloys with varying Zn content were prepared. The alloy ofComparative Example 1 having a Zn content of less than 24% by mass has aproblem in tensile strength. The alloy of Example 1 having a Zn contentof 24% by mass or more has a certain level of tensile strength, and thealloys of Examples 2 and 3 having a Zn content of 27% by mass or morehave a sufficient tensile strength. On the other hand, the alloy ofComparative Example 2 having a Zn content of greater than 34% by mass,which is too high, has a problem in elongation.

Secondly, alloys with varying Al content were prepared. In the alloy ofComparative Example 3 having an Al content of less than the detectionlimit, both the tensile strength and the 0.2% proof stress wereinsufficient. The alloy of Example 4 having an Al content of 0.39% bymass has a certain level of tensile strength and 0.2% proof stress, andthe alloys of Example 5, 3, and 6 having an Al content of 0.6% by massor more have a sufficient tensile strength and 0.2% proof stress. On theother hand, the alloy of Comparative Example 4 having an Al content ofgreater than 1.8% by mass, which is too high, has a problem inelongation, while the alloy of Example 6 having an Al content of lessthan 1.66% by mass, which is less than 1.8% by mass, has a certain levelof elongation.

Thirdly, alloys with varying P content were prepared. In the alloy ofExample 8 having a slightly higher P content, the erosion-corrosionresistance was slightly reduced. Further, the alloy of ComparativeExample 5 having a high P content of greater than 0.2% by mass has toolow an elongation.

Fourthly, alloys with varying Sn content were prepared. In the alloy ofComparative Example 6 having a Sn content of 0.11% by mass and the alloyof Comparative Example 7 having a Sn content of 0.31% by mass, theerosion-corrosion resistance was insufficient, and both the values ofthe abrasion weight loss and the maximum depth were unfavorable. Thealloy of Example 9, which has a Sn content of 0.91% by mass and in whichthe Sn content and the Al content satisfy the equation: T=Al+2×Sn=2.82,has a certain level of erosion-corrosion resistance. Further, the alloysof Examples 3 and 10 having a Sn content of 1.0% by mass or more have asufficient erosion-corrosion resistance. On the other hand, the alloysof Comparative Examples 8 and 9 having a Sn content of greater than 1.7%by mass have too low an elongation. The alloy of Example 10 having a Sncontent of 1.54% by mass has a certain level of elongation.

Fifthly, alloys with varying Pb content were prepared. All of the alloysof Examples 11, 3, and 12 having a Pb content as shown in Table 4exhibited good mechanical properties and the erosion-corrosionresistance. However, in the alloy of Example 12 whose Pb content isclose to 0.25% by mass, a slight decrease in elongation was observed.

<Evaluation of Machinability in Relation with P and Pb Content>

Next, alloys with varying P and Pb contents were prepared, and subjectedto the drilling test and the lathe machining test to evaluate thechanges in the machinability. The contents of the respective componentsand the test results of the respective alloys are shown in Table 5.

TABLE 5 Machinability test Chemical components Drilling time MachiningZn Al P Pb Sn Bi Cu sec chips P Comparative 29.54 1.01 0.000 0.071 1.170.000 Bal. 28.7 I I Example 10 (Continuous) Example 13 29.70 1.00 0.0090.074 1.20 0.000 Bal. 13.4 G G (Broken) Example 7 29.93 1.00 0.036 0.0541.14 0.000 Bal. 19.9 G G (Broken) Example 3 30.17 1.06 0.057 0.063 1.210.000 Bal. 17.0 G G (Broken) Example 8 29.79 1.02 0.121 0.070 1.12 0.000Bal. 21.9 F G (Broken) Comparative 29.50 1.02 0.235 0.060 1.16 0.000Bal. 23.7 F G (Broken) Example 5 Pb Comparative 28.72 0.98 0.060 0.0001.04 0.000 Bal. 42.4 I G (Broken) Example 11 Example 11 29.40 1.04 0.0560.025 1.05 0.000 Bal. 21.4 F G (Broken) Example 3 30.17 1.06 0.057 0.0631.21 0.000 Bal. 17.0 G G (Broken) Example 12 30.11 1.02 0.055 0.233 1.190.000 Bal. 12.0 G G (Broken) Pb and P Comparative 30.05 1.10 0.000 0.0001.05 0.000 Bal. 47.3 I I Example 12

Firstly, the changes due to varying P content are examined. The alloy ofComparative Example 10 having a P content of 0.009% by mass and thealloy of Example 13 having a P content of less than the detection limitwere prepared. The thus prepared alloys and the alloys of the abovementioned Examples 7, 3, and 8, and Comparative Example 5 were subjectedto the drilling test. In the alloy of Comparative Example 10 having a Pcontent of less than the detection limit, it took too long to drill ahole, and continuous machining chips were produced. In the alloys ofExample 13, 7, and 3 having a P content of 0.005% by mass or more, itwas possible to drill a hole in a sufficiently short period of time.Further, in the alloys of Examples 13 and 3, the resulting machiningchips were broken into pieces. This is thought to be due to the Al—Pcompounds, formed as a result of containing P, serving as chip breakersduring the machining. On the other hand, in each of the alloys ofExample 8 and Comparative Example 5 having a P content of greater than0.1% by mass, the time required to drill a hole was slightly increasedto a level which cannot be disregarded.

In addition, the machining chips of the alloys of Comparative Example10, Example 13, and Example 3 were evaluated based on their shapes. Thephotographs of the machining chips of the alloys of Comparative Example10, Example 13, and Example 3 are shown in FIGS. 6 (a), (b), and (c),respectively. The alloy of Comparative Example 10 producedhelically-coiled, continuous machining chips which are unfavorable;whereas the alloy of Example 13 having a higher P content producedgenerally shorter machining chips, and the alloy of Example 3 having aneven higher P content produced even shorter machining chips, both ofwhich are favorable.

Next, the changes due to varying Pb content are examined. The alloy ofComparative Example 11 having a Pb content of less than the detectionlimit was newly prepared. The thus prepared alloy and the alloys of theabove mentioned Examples 11, 3, and 12 were subjected to the drillingtest. In the alloys of Comparative Example 11 having a Pb content ofless than the stipulated value, the drilling time was significantlyincreased. In the alloys of Example 11 having a Pb content of 0.025% bymass, the drilling time was relatively reduced, and a certain level ofthe machinability was secured. In each of the alloys of Examples 3 and12 having an even higher Pb content, the drilling time was reduced to asufficiently short time. Further, the machining chips of the alloys ofComparative Example 11 and Example 11 were evaluated based on theirshapes. The photographs of the machining chips of the alloys ofComparative Example 11 and Example 11 are shown in FIGS. 6 (d) and (e),respectively. The machining chips produced by respective alloys had noproblems.

Further, as an example containing neither P nor Pb, the alloy ofComparative Example 12 was prepared. The alloy of Comparative Example 12was subjected to the evaluation of machining chips and the drillingtest. The photograph of the machining chips of the alloy of ComparativeExample 12 is shown in FIG. 6 (f). The results revealed that, the alloyof Comparative Example 12 containing neither P nor Pb producedunfavorable continuous machining chips which were even longer than thoseproduced by the alloy of Comparative Example 10 containing Pb but not P.In the drilling test, as well, the alloy of Comparative Example 12exhibited a drilling time which was even significantly longer than thatof Comparative Example 10.

Other results will be examined individually with reference to Examplesand Comparative Examples. The data thereof are shown in Table 6.

TABLE 6 Mechanical properties Chemical component Tensile strength Zn AlP Pb Sn Bi Cu Ni B (MPa) Zn Example 2 27.50 1.03 0.058 0.053 1.21 0.000Bal. 385.0 G Example 3 30.17 1.06 0.057 0.063 1.21 0.000 Bal. 392.0 GComparative 34.87 1.00 0.058 0.057 1.18 0.000 Bal. 401.0 G Example 2 BiExample 3 30.17 1.06 0.057 0.063 1.21 0.000 Bal. 392.0 G Comparative29.88 1.08 0.062 0.077 1.17 0.350 Bal. 348.5 G Example 13 Ni-1 Example 330.17 1.06 0.057 0.063 1.21 0.000 Bal. 392.0 G Example 14 30.10 1.110.059 0.083 1.12 0.000 Bal. 0.82 351.5 G Comparative 30.20 1.06 0.0550.067 1.18 0.000 Bal. 1.88 362.5 G Example 14 Ni-2 Example 15 29.20 1.100.052 0.091 1.05 0.000 Bal. 0.52 377.0 G Example 16 30.20 1.06 0.0480.088 1.08 0.000 Bal. 1.03 366.5 G B-1 Example 3 30.17 1.06 0.057 0.0631.21 0.000 Bal. 392.0 G Example 17 30.10 1.11 0.059 0.083 1.12 0.000Bal. 0.0060 392.0 G B-2 Example 18 30.17 1.05 0.056 0.100 1.10 0.000Bal. 0.0007 388.0 G Example 19 29.70 1.05 0.055 0.075 1.12 0.000 Bal.0.0012 390.0 G Example 20 30.10 1.10 0.055 0.097 1.06 0.000 Bal. 0.0110385.5 G B + Ni Example 21 30.20 1.06 0.055 0.067 1.18 0.000 Bal. 0.810.0050 366.0 G Example 22 29.20 1.05 0.055 0.088 1.11 0.000 Bal. 0.490.0041 382.0 G Example 23 29.40 1.11 0.047 0.072 1.08 0.000 Bal. 1.040.0053 388.5 G Dezincification corrosion EC Mechanical properties testAbrasion Maximum Elongation 0.2% proof Maximum Average weight depth (%)stress (MPa) depth (μm) depth (μm) loss (mg) (μm) Zn Example 2 25.1 G125.0 G 104.7 G 47.1 V Example 3 26.9 G 147.5 G 133.8 G 67.7 GComparative 19.1 I 175.5 G 396.9 F 207.5 I Example 2 Bi Example 3 26.9 G147.5 G 133.8 G 67.7 G Comparative 18.2 I 154.0 G 122.3 G 65.4 G Example13 Ni-1 Example 3 26.9 G 147.5 G 133.8 G 67.7 G Example 14 21.2 F 137.5G 116.5 G 48.1 V Comparative 19.7 I 149.0 G 96.5 V 44.1 V Example 14Ni-2 Example 15 25.5 G 141.5 G 122.2 G 49.4 V 175 G 124 G Example 1622.4 F 140.2 G 105.2 G 45.2 V 168 G 119 G B-1 Example 3 26.9 G 155.0 G133.8 G 67.7 G Example 17 27.3 G 155.0 G 79.2 V 41.7 V B-2 Example 1827.5 G 153.0 G 103.8 G 49.8 V 184 G 129 G Example 19 25.5 G 151.5 G 95.3V 44.2 V 182 G 125 G Example 20 24.8 F 152.5 G 70.4 V 38.9 V 179 G 131 GB + Ni Example 21 22.5 F 152.0 G 65.7 V 39.8 V G G Example 22 23.5 F153.5 G 70.5 V 40.5 V 171 G 129 G Example 23 21.0 F 153.0 G 63.5 V 32.2V 166 G 121 G

<Results of Dezincification Corrosion Test>

The alloys of Example 2, Example 3, and Comparative Example 2 were usedto examine the changes in the dezincification corrosion depth due tovarying Zn content. The alloy of Example 2 having a sufficiently low Zncontent exhibited a markedly reduced dezincification corrosion depth.The alloy of Example 3 also had a low level of corrosion. In contrast,in the alloy of Comparative Example 2 having a Zn content of greaterthan 34% by mass, the value of the maximum depth was close to theacceptable limit, and the average depth was significantly increased.

<Examination of Alloy Behavior Due to Addition of Bi>

The alloy of Comparative Example 13 having a composition close to thatof Example 3 and containing 0.35% by mass of Bi was prepared andexamined. The results confirmed that the alloy has a significantlyreduced elongation, and thus has problems not only in recyclability butalso in mechanical properties.

<Examination of Alloy Behavior Due to Addition of Ni: No. 1>

The alloy of Example 14 having a composition close to that of Example 3and further containing 0.82% by mass of Ni, and the alloy of ComparativeExample 14 having a composition close to that of Example 3 and furthercontaining 1.88% by mass of Ni were prepared. While the dezincificationcorrosion resistance was significantly improved in both the alloys ofExample 14 and Comparative Example 14, the elongation was excessivelydecreased in the alloy of Comparative Example 14 having a Ni content of1.88% by mass.

<Examination of Alloy Behavior Due to Addition of Ni: No. 2>

The alloys of Examples 15 and 16 each having a lower Sn content and ahigher Pb content as compared to that of Example 14 were prepared. Inthe alloy of Example 16 having a higher Ni content as compared to thatof Example 15, the dezincification corrosion resistance was moreimproved. Further, the measurement of the erosion-corrosion resistanceof the alloys of Examples 15 and 16 revealed that the both alloys have agood erosion-corrosion resistance. However, it was also shown that whilethe alloy of Example 16 has a certain level of elongation, but it isslightly decreased as compared to that of Examples 15.

<Examination of Alloy Behavior Due to Addition of B: No. 1>

The alloy of Example 17 having a composition close to that of Example 3and further containing 0.006% by mass of B was prepared. In each of thealloys of Example 3 and Example 17, a marked improvement in thedezincification corrosion resistance was observed.

<Examination of Alloy Behavior Due to Addition of B: No. 2>

The alloys of Examples 18 to 20 having a composition close to that ofExample 3 and further containing increasing amounts of B were prepared.The alloy of Example 18 has a B content of 0.0007% by mass, the alloy ofExample 19 has B content of 0.0012% by mass, and the alloy of Example 20has a B content of 0.011% by mass. The dezincification corrosionresistance was significantly improved with increasing B content, andthus the dezincification corrosion resistance of the alloy of Example 20was particularly improved. It was also shown, however, that while thealloy of Example 20 has a certain level of elongation, it is somewhatdecreased as compared to those of Examples 18 and 19.

<Examination of Alloy Behavior Due to Addition of B and Ni>

The alloys of Examples 21 to 23 having a composition close to that ofExample 3 and further containing both B and Ni were prepared. All thealloys exhibited a particularly excellent dezincification corrosionresistance. However, it was also shown that each of the alloys has acertain level of, but somewhat lower elongation.

DESCRIPTION OF SYMBOLS

-   11 nozzle-   12 test specimen-   13 aqueous solution of CuCl₂

1. A low-lead brass alloy for use in a member for water works, the brassalloy comprising: 24% by mass or more and 34% by mass or less of Zn;0.5% by mass or more and 1.7% by mass or less of Sn; 0.4% by mass ormore and 1.8% by mass or less of Al; 0.005% by mass or more and 0.2% bymass or less of P; and 0.01% by mass or more and 0.25% by mass or lessof Pb; with the balance being copper and an unavoidable impurity(ies);wherein, in cases where the brass alloy has a content of Sn of less than1.0% by mass, the contents of Al and Sn in % by mass satisfy thefollowing Inequality (1):Al+2×Sn≧2.8  (1).
 2. The low-lead brass alloy for use in a member forwater works according to claim 1, wherein the content of Sn is 1.0% bymass or more.
 3. The low-lead brass alloy for use in a member for waterworks according to claim 1, further comprising 0.0005% by mass or moreand 0.015% by mass or less of B.
 4. The low-lead brass alloy for use ina member for water works according to claim 1, further comprising 0.1%by mass or more and 1.8% by mass or less of Ni.
 5. The low-lead brassalloy for use in a member for water works according to claim 2, furthercomprising 0.0005% by mass or more and 0.015% by mass or less of B. 6.The low-lead brass alloy for use in a member for water works accordingto claim 2, further comprising 0.1% by mass or more and 1.8% by mass orless of Ni.
 7. The low-lead brass alloy for use in a member for waterworks according to claim 3, further comprising 0.1% by mass or more and1.8% by mass or less of Ni.
 8. The low-lead brass alloy for use in amember for water works according to claim 5, further comprising 0.1% bymass or more and 1.8% by mass or less of Ni.